SNUBBER CIRCUIT

SNUBBER CIRCUIT

MODEL: PCESCOl
CLW SPEC NO. CLW/ES/3/0067

Introduction:

Switching of any voltage across an inductive load results in high reverse voltage build-up across the load and the breaking contact.The coil of a contactor being inductive in nature in any electrical circuit, the coil is subject to voltage stress during switch-off which could cause gradual insulation damage if the coil is left in open circuit or the inductive energy would dissipate as heat in the coil if the circuit is closed. One safe method of relieving the voltage stress is to transfer the energy in a closed circuit to Avalanche type semi-conductor junctions which can absorb high but short pulses of energy.

A typical circuit is shown below. The Blocking Diode blocks forward voltage; the Avalanche Device absorbs energy due to reverse voltage build up across coil. An R-C network across the contact does not allow sudden rise in voltage and hence limits the voltage stress.